Fission product isotope ratios as event characterization tools Part I: Particulate debris, isotopic activity ratios

The main goal of this work is to develop quantitatively reliable tools that can be used to identify the origin of a nuclear event, e. g. discriminate between a nuclear explosion and an accidental reactor release. A model has been developed, which takes into account the wide range of conditions and parameters, which may exist in connection with nuclear events. Using the model, specific isotope activity ratios are defined, promising to be effective in event characterization, while reducing the influence of various nuclear scenarios to a minimum. Besides, an attempt was made to quantify the concept of “short irradiation reactor” and to set its limits, as related to an event characterization method.